Lambda Sensor Fault Diagnosis via Gradient and Delay Analysis
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Solution Overview
Problem
Existing methods for diagnosing the functionality of lambda sensors and vehicle catalysts in exhaust gas purification systems are inadequate, leading to potential inaccuracies and delays in lambda control.
Innovation Solution
A method involving the determination of signal gradient and signal delay between upstream and downstream lambda sensors to diagnose defects in the second lambda sensor and/or vehicle catalyst, using empirically determined thresholds to ensure accurate and rapid detection of faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If signal gradient and signal delay are used to diagnose lambda sensors and catalysts, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The diagnosis method is segmented into distinct evaluation criteria: signal gradient analysis and signal delay analysis. Each criterion independently evaluates specific aspects of lambda sensor and catalyst functionality, allowing complex diagnosis to be broken down into manageable, interpretable components without increasing overall system complexity
Solution Approach 2:
Instead of adding complex hardware to improve diagnosis accuracy, the patent inverts the approach by using existing sensor signals in novel ways (analyzing gradient and delay characteristics) to achieve precise diagnosis through software/evaluation methods alone
2Productivity
If lambda control speed is increased, then productivity is improved, but measurement precision deteriorates due to signal delays
Solution Approach 1:
The system performs preliminary analysis of signal characteristics (gradient and delay) to predict and compensate for signal delays before they affect control decisions. This allows the lambda control to proceed at high speed while maintaining measurement precision through advance correction
Solution Approach 2:
The patent implements feedback by continuously monitoring signal gradient and delay characteristics from lambda sensors and using this information to adjust control parameters in real-time, ensuring that increased control speed does not compromise measurement accuracy
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables precise and reliable diagnosis of the second lambda sensor and vehicle catalyst, reducing false positives and improving the efficiency of the diagnosis system, and enhancing the accuracy of lambda control.
Implementation Method 1
a first lambda sensor arranged upstream of the vehicle catalytic converter and a second lambda sensor arranged downstream of the vehicle catalytic converter
Data Source
Figure 1~2
AI summary
The invention relates to a method for operating an exhaust-gas cleaning device (3) for a motor vehicle, wherein the exhaust-gas cleaning device (3) has a vehicle catalytic converter (4), a first lambda sensor (5) upstream of the vehicle catalytic converter (4) and a second lambda sensor (6) downstream of the vehicle catalytic converter (4). According to the invention, a signal gradient (15, 16, 17) is determined temporally between a first signal jump (9) of a measurement value of the first lambda sensor (5) in a first direction and a second signal jump (10) of the measurement value in a second direction opposite the first direction, and after the second signal jump (10) a signal delay of a measurement value of the second lambda sensor (6) is determined, wherein a defect of the second lambda sensor (6) is recognized if the signal gradient (15, 16, 17) is less than a signal gradient threshold value and the signal delay is greater than a signal delay threshold value, and/or a defect of the vehicle catalytic converter (4) is recognized if the signal gradient (15, 16, 17) is less than the signal gradient threshold value and the signal delay is less than the signal delay threshold value. The invention also relates to an exhaust-gas cleaning device (3) for a motor vehicle.